Utils: Add FilePath.hasFileAccess()

FilePath::hasFileAccess allows a user to test if a specific device
can access files. This is faster than calling "exists()" as it does
not have to actually check anything on the device.

cherry picked from commit 21ef25a0f5

Task-number: QTCREATORBUG-28531
Change-Id: I363ca634d921464fe4ec68397c09fba49dccee25
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/libs/utils/filepath.cpp

@@ -826,6 +826,12 @@ DeviceFileAccess *FilePath::fileAccess() const
     return access;
 }
 
+bool FilePath::hasFileAccess() const
+{
+    DeviceFileAccess *access = s_deviceHooks.fileAccess(*this);
+    return access;
+}
+
 /// Constructs a FilePath from \a filePath. The \a defaultExtension is appended
 /// to \a filename if that does not have an extension already.
 /// \a filePath is not checked for validity.

src/libs/utils/filepath.h

@@ -207,6 +207,7 @@ public:
     // There are usually other means available. E.g. distinguishing based
     // on FilePath::osType().
     bool needsDevice() const;
+    bool hasFileAccess() const;
 
     bool isSameDevice(const FilePath &other) const;
     bool isSameFile(const FilePath &other) const;

src/libs/utils/fsengine/fsengine.cpp

@@ -36,6 +36,7 @@ FilePaths FSEngine::registeredDeviceRoots()
 
 void FSEngine::addDevice(const FilePath &deviceRoot)
 {
+    if (deviceRoot.hasFileAccess())
         deviceRoots().append(deviceRoot);
 }